Process for insolubilizing polymers with masked isocyanates

ABSTRACT

Masked isocyanates in which the isocyanate group or groups may be generated by heating above 100*C are formed by tetrazolinones and bis(tetrazolinones) corresponding to the formula:   WHEREIN X is hydrogen, halogen, nitro, alkyl (1-4 C) or a group of formula:   AND R is an aliphatic, aromatic or araliphatic hydrocarbon radical. The bis(tetrazolinones) may be utilized to cross-link upon heating polymers containing active hydrogen atoms. The heating may occur image-wise or record-wise so that layers composed of mixtures of polymers and bis(tetrazolinones) can be used as heatsensitive recording materials.

United States Patent [191 Smets et al.

[451 Feb; 5, 1974 1 PROCESS FOR INSOLUBILIZING POLYMERS WITH MASKEDISOCYANATES [75] Inventors: Georges Joseph Smets, l-leverlee; Jean MarieVandensavel, Tienen,

both of Belgium [73] Assignee: AGFA-Gevaert N.V., Mortsel,

Belgium [22] Filed: May 26, 1972 21 Appl. No.: 257,235

[30] Foreign Application Priority Data June 2, 1971 Great Britain18691/71 [52] US. Cl 96/35.1, 96/115 R, 250/316, 250/317, 260/47 EN,260/793 M, 260/883,

[51] Int. Cl G03c l/70 [58] Field of Search. 96/35.l, 115 R; 250/316,317; 260/308 D, 47 EN, 79.3 M, 88.3

[56] References Cited UNITED STATES PATENTS 3,278,305 10/1966 Laridon eta1. 96/35.l 3,147,116 9/1964 Roth 96/35.l 3,486,891 12/1969 Wilhelm.96/35.1 3,628,992 12/1971 McKillip 260/47 EN Primary Examiner--Ronald H.Smith Attorney, Agent, or Firm-Alfred W. Breiner [57] ABSTRACT Maskedisocyanates in which the isocyanate group or groups may be generated. byheating above 100C are formed by tetrazolinones and bis(tetrazolinones)corresponding to the formula:

wherein x is hyai erifiiiSaiLEiB,ink 1-4 0 or a group of formula:

7 Claims, No Drawings PROCESS FOR INSOLUBILIZING POLYMERS WITH MASKEDISOCYANATES The invention relates to masked isocyanates anddiisocyanates, to a process for the manufacture of masked isocyanatesand di-isocyanates, and to the modification of polymers using thesemasked isocyanates and di-isocyanates.

By masked isocyanates and di-isocyanates are meant compounds, in whichthe isocyanate group or groups may be generated usually by heatingbetween 100 and 200 C.

The reactivity of the isocyanate group with compounds containing activehydrogen atoms is known. In some chemical reactions the reactivity ofthe isocyanate groups with compounds containing hydrogen atoms is fartoo high. For example, this is the case when an isocyanate ordi-isocyanate is used to cure polymeric products. The polymer is curedgenerally before a useful commercial product can be made from thiswherein:

X represents a hydrogen atom, a halogen atom, a nitro group, an alkylgroup of l to 4 carbon atoms, or a group of the formula:

and R represents an aliphatic, aromatic or araliphatic hydrocarbonradical.

These masked isocyanates are tetrazolinones. They are prepared accordingto a process comprising heating in a common solvent stoichiometricquantities of an azide-substituted aliphatic, aromatic or araliphatichydrocarbon and benzene monoor di(sulphonyl isocyanate the benzenenucleus of which may be substituted with a halogen atom, a nitro group,or an alkyl group of l to 4 carbon atoms.

Common solvents for both the isocyanate and the azide-substitutedaliphatic, aromatic or araliphatic hydrocarbon are non-polar organicsolvents such as carbon tetrachloride and toluene.

Representative tetrazolinones are e.g.:

l-phenylsulphonyl-4-n-butyI-Z-tetrazolin-S-onel-phenylsulphonyl-4-ethyl-2-tetrazolin-S-onel-phenylsulphonyl-4-phenyl-2-tetrazolin-S-one l -phenylsulphonyl-4(2'-phenylethyl )-2-tetrazolin- -onel-phenylsulphonyl-4(4'-phenyl-n-butyl)-2- tetrazolin -5-one l-(p-chlorophenylsulphonyl )-4-n-butyl-2-tetrazolin- '5-one l-(p-methylphenylsulphonyl )-4-n-butyl-2-tetrazolin- 5-one v 'l-(p-nitrophenylsulphonyl )-4-n-butyl-2-tetrazolin- 5-onel-(m-nitrophenylsulphonyl )-4-n-butyl-2-tetrazolin- S-one compounds ofthe invention containing masked isocyamixture of polymer containing freehydroxyl or amino nate groups may especially be utilized to cure orcrosslink polymers containing active hydrogen atoms such as present infree hydroxyl or amino substituents on polymeric chains. When abis(tetrazolinone) according to the invention is mixed intimately with apolymer containing e.g. free hydroxyl or amino groups and when themixture is then heated above 100 C, a crosslinked, completely insolublepolymer is formed.

If this heating at elevated temperatures is executed image-wise orrecord-wise on a layer formed from the groups and of bis-tetrazolinoneaccording to the invention, cross-linking of the polymer only occurs atthe places struck by heat and an image-wise or record-wisedifferentiation in the solubility or in the melt temperature ofthe-polymer layer may be obtained. In this way the layer composed of themixture of polymer and tetrazolinone can be used as a heat-sensitiverecording material.

The heat needed to decompose the tetrazolinones of the inventionimage-wise or record-wise and to crosslink the polymeric binding agentat these places, can be supplied by infra-red radiation e.g. by aninfra-red laset. For instance, an original containing infra-redlightabsorbing image areas may be exposed to infra-red radiation whilebeing in heat-conductive contact with a layer containing a mixture ofpolymer and tetrazolinones of the invention. At the places correspondingwith the image areas of the original, the layer reaches a temperature,at which the tetrazolinones are decomposed. The isocyanates thus formedreact with the active hydrogen atoms of the polymer and cross-link thepolymer to .the insoluble state. When a finely divided substanceabsorbing visible light and converting it into heat e.g. finely dividedcarbon black, is mixed throughout a layer, which is composed of amixture of polymer and tetrazolinone, the image-wise or record-wisedecomposition of the tetrazolinones may be obtained by exposure of thelayer to flashlight, more particularly to flashlight emitted by gasdischarge lamps, e.g. xenon gas discharge lamps. These lamps can supplyan energy of 300-l000 watt.sec. in a period of 10 to l0 2 seconds.During the exposure through an original the finely divided substanceabsorbs visible light and converts it into heat at theplacescorresponding with the transparent areas of the original. As a result ofthis conversion into heat the tetrazolinone is decomposed in theseplaces and the polymer is cross-linked. At the non-exposed andconsequently unhardened areas the polymer can now be washed away, orthese unhardened areas can be transferred by pressing against areceiving material whilst heating. This transfer can be performed as aresult of the reduced solubility of the exposed and consequentlycross-linked-parts and of the enhanced melting temperature of thesehardened parts.

As a result of the image-wise or record-wise heating at elevatedtemperatures of the layer formed from a mixture of polymer containingactive hydrogen atoms and of bis-tetrazolinones according to theinvention, a differentiation in the solubility or in the melttemperature of different areas of the layer is obtained. The areas ofthe layer, that have not been cross-linked by heat may be washed awaywith a solvent for the unmodified polymer. In this way a negative reliefimage of the original is formed, which may be used as a negativeprinting plate.

When, however, the unhardened areas are transferred by pressing againsta receiving material whilst heating, a positive relief image of theoriginal is formed. This relief image can be used as a positive printingplate after thorough hardening of the transferred areas of the layer, ifneeded, by heating to the decomposition temperature of thebis-tetrazolinone.

In the manufacture according to the invention of tetrazolinonescontaining masked isocyanate groups, it might be interesting to replacethe mono-azidesubstituted aliphatic, aromatic or araliphatic hydrocarbonby corresponding dior poly-azides. As a result of the reaction withbenzene monoor di(sulphonyl isocyanates) bisandpoly-tetrazolinones areformed that contain also masked isocyanate groups. These bisandpoly-tetrazolinones are also decomposed by heat whereby the isocyanategroups are set free. Moreover, if a polymer containing azideside-substituents is reacted with the sulphonyl isocyanates, a polymeris formed containing tetrazolinon side-substituents. In fact a polymeris obtained carrying masked isocyanate groups distributed .over itspolymer chain, which masked isocyanate groups can be set free again byheating the polymer at a temperature above 100 C.

The synthesis of the azide-substituted aliphatic, aromatic oraraliphatic hydrocarbons needed in the manufacture of the tetrazolinonesof the invention is illustrated by the synthesis of n-butylazide. Thisnbutylazide is prepared by addition of an equimolar amount ofn-butylbromid'e to sodium azide suspended in dimethylformamide.

The different arylsulphonyl isocyanates are synthetized by phosgenationof the corresponding sulphonamides. The sulphonamide is dissolved inchlorobenzene (o-dichlorobenzene in the case of nitro-derivatives),whereupon the water present is distilled off azeotropically.Subsequently, a catalytical amount of n-butyl isocyanate isadded.'Phosgene is condensed first in a slight excess, e.g. in a mixtureof isopropanol and solid carbon dioxide. It is then allowed to bubblethrough a solution of the amide whilst refluxing. The excess of phosgeneis eliminated by allowing nitrogen to bubble through the solution. Thesolvent and the n-butyl isocyanate are distilled off under reducedpressure, whereupon a high yield of the arylsulphonyl isocyanate isobtained by vacuum destillation.

EXAMPLE 1 -cm was observed. A broad peak at 1,750 cm was attributed tothe absorption whereas the S0 absorptions shift, i.e.

v as S0 from 1,380 cm towards 1,400 cm, and

v as S0 from 1185 cm towards 1200 cm. After complete reaction thesolvent was distilled off under reduced pressure at room temperature.Subsequently, the residue was dissolved in ether and cooled down to 25C, whereas the reaction product crystallized out.

The resulting 1phenylsulphonyl-4-n-butyl-2- tetrazolinon-S-one was awhite powder melting at 42.543.5 C. A clear transparent crystallinepowder was obtained by slow crystallization from ether. The powdercorresponded to the following formulai The following results wereobtained by elementary analysis calculated 46.79 percent;'found 46.80percent calculated 5.01 percent; found 4.95 percent calculated 19.85percent; found 20.05 percent calculated 17.00 percent; found 16.85percent calculated 11.35 percent; found 11.35 percent EXAMPLE 2calculated 4.15 percent; found 4.15 percent N calculated 17.69 percent;found 7.52 percent 0 calculated 15.15 percent; found 15.42 percent C1calculated] 1.19 percent; found 2 1 1.18 percent S calculated 10.12percent; found 9.68 percent By infrared spectroscopy the mostcharacteristic peak was found to be a large absorption band at 1,753 cm,which was attributed to the absorption. The other absorptions wereanalogous to those described in example l with the difference,howcalculated 41.70 percent; found 41.46 percent ever, that apara-substitutedproduct was concerned here, which gave rise to a strongabsorption at 832 cm.

EXAMPLE 3 Equimolar amounts of n butylazide and(p-methylphenyl)-sulphonyl isocyanate were dissolved at room temperaturein toluene with a molar concentration of 0.6. The resultingl-(p-methylphenyl-sulphonyl)-4-nbutyl-Z-tetrazolin-S-one was awhitepowder (or clear crystals in the case of a slow crystallization)melting at- The infrared-spectrum showed a large absorption band at1,745 cm due to the group whereas the further spectrum was analogous tothat of example 1.

EXAMPLE 4 Equimolar amounts of (p-nitrophenyl)-sulphonyl iso- I cyanateand n-butylazide were dissolved at room temperature in toluene with amolar concentration of 0.6.

in the lR-spectrum a large band due the group was found at l ,750 cm.

The light yellow crystals ofl-(p-nitrophenylsulphonyl)-4-n-butyl-2-tetrazolin-5-one melted between124 and 125 EXAMPLE 5 rib was found at 1,758 6111-" whereas the furtherspectrum was identical with that of example 4, except for the phenylsubstitution (meta-substitution instead of para).

EXAMPLE 6 1 mole of m-benzene disulphonylisoeyanate and 2 moles ofn-butylazide were dissolved at room temperature in carbon tetrachloride.A product melting at 124, C was formed. In the lR-spectrum an absorptionband due to the group swam; TFS YGMTTTY EWdisulphonyl)-bis(4n-butyl-2-tetrazolin-5-one) was obtained.

EXAMPLE 7 2 ml of l,l,2-trichloroethane and 0.4 g. ofl,l'-(mphenylenedisulphonyl)-bis (4-n-butyl-2-tetrazolin- 5-one) asprepared in example 6 were added to 2 ml of a 10 percent by weightsolution in methylene chloride of the polyether obtained bypolycondensation of epichlorohydrin and2,2-bis(4-hydroxyphenyl)-propane. The solution was coated on an aluminumfoil or on a non-subbed polyethylene terephthalate foil of 0.l mm sothat in both cases the dried layer had a thickness of 2 to 5 micron.This layer could be washed off easily with methylene chloride.

if the layer was heated for 5 to 10 minutes at 120 C, it could not bewashed off any longer with methylene chloride, because as a result ofthe heating the 1,1'(mphenylene-disulphonyl)-bis(4-N-butyl-2-tetrazolin- 5-one) haddecomposed and because these decomposition products immediately enteredinto reaction with the polyether and cross-linked the latter to theinsoluble state.

EXAMPLE 8 0.04 g of1,1-(m-phenylene-disulphonyl)-bis(4-nbutyl-2-tetrazolin-5-one) was addedto 4 ml of a 5 percent by weight solution in methylene chloride of lowviscous polyvinylbutyraldehyde acetal, which comprised 20 mole percentof recurring units with free hydroxyl groups). The solution was coatedin the same way as described in example 7 on an aluminum foil or on anon-subbed polyethylene terephthalate foil having a thickness of 0.1 mm.

if the dried layers were heated for 5 to 10 minutes at 120 C, they couldnot be washed away any longer with methylene chloride.

EXAMPLE 9 1 ml of a 40 percent by weight aqueous carbon black dispersionwas dispersed in the solution of polyether and 1,1'-(m-phenylene-disulphonyl)-bis(4-n-butyl-2- tetrazolin-S-one) asprepared in example 7. The resulting black coating composition wasapplied to a polyester foil. After having been dried, the resultinglayer was exposed through a transparent line original by means of xenongas discharge lamp placed at a distance of 10 cm. The dischargebetweenthe electrodes of the xenon gas discharge lamp produced a radiationenergy of 610 watt. sec in 1/2000 sec. at a distance of 4 cm. Attheexposed areas the light was converted into heat by the carbon black sothat at these areas the polyether was cross-linked to the insolublestate.

After exposure the polyester foil was pressed with itspolyether-tetrazolinon layer to a baryta-paper and gradually heated toC,whereupon the polyester foil was stripped off. The exposed, hardenedportions of the layer adhered to the polyester foil, whereas theunexposed and consequently non-hardened areas became sticky as a resultof the heating and were thus transferred to the baryta paper. Uponheating above 100 C the polyether in the transferred areas wascrosslinked to the insoluble state and in this way a positive reliefimage of the line original was formed.

We claim:

1. Process for the insolubilization of polymers con taining activehydrogen atoms, which comprises intimately mixing said polymercontaining active hydrogen atoms with a masked isocyanate correspondingto the formula:

mean; Y

X represents a hydrogen atom, a halogen atom, a

nitro group, an alkyl group of l to 4 carbon atoms, or a group accordingto the formula:

atoms is a polyether obtained by the polycondensation of epichlorohydrinand 2,2-bis(4-hydroxyphenyl)-propane. H

4. Process according to claim 1, wherein the heating 5 above C occursimage-wise or record-wise.

5. Process according to claim 4, wherein finely divided carbon black isdispersed throughout the mixture of polymer containing reactive hydrogenatoms and of masked isocyanate, and the image-wise or record-wiseinsolubilization is obtained by exposure to a gas discharge flash lampsupplying an energy of 300-1000 watt. sec. in a period of l0 to 10seconds.

6. Process according to claim 4, wherein the imagewise of record-wiseinsolubilization is obtained with an infra-red laser.

7. The process of claim 1 wherein R is CH

2. Process according to claim 1, wherein the intimate mixture of polymercontaining active hydrogen atoms and of masked isocyanate has beenapplied as a layer to a support.
 3. Process according to claim 1,wherein the polymer coNtaining active hydrogen atoms is a polyetherobtained by the polycondensation of epichlorohydrin and2,2-bis(4-hydroxyphenyl)-propane.
 4. Process according to claim 1,wherein the heating above 100* C occurs image-wise or record-wise. 5.Process according to claim 4, wherein finely divided carbon black isdispersed throughout the mixture of polymer containing reactive hydrogenatoms and of masked isocyanate, and the image-wise or record-wiseinsolubilization is obtained by exposure to a gas discharge flash lampsupplying an energy of 300-1000 watt. sec. in a period of 10 4 to 10 2seconds.
 6. Process according to claim 4, wherein the image-wise ofrecord-wise insolubilization is obtained with an infra-red laser.
 7. Theprocess of claim 1 wherein R is C4H9.